Known circular knitting machines are all equipped with yarn feeder devices of this general type, in which at least one yarn is processed at each knitting feed. The yarn path extends from the yarn packages, mounted on an either stationary or rotating yarn carrier cage, via a plurality of yarn deflection points embodied by yarn guide elements such as eyes, to the yarn feeder which supplies the yarn to the individual needles in succession at any given knitting feed. The yarn feeder, embodied as a narrow, thin metal plate, conventionally has a yarn guide bore through which the yarn passes on its way to the needles. A yarn feeder of this kind must be disposed as close to the needles as possible yet without touching them, which would cause premature wear. Since in addition to the feeding of the yarn the yarn feeder has still other tasks to perform, namely to open half-closed needle latches and to avoid a latch closing during the run-in of the yarn, it is fabricated from hardened steel and equipped with a separating edge, with which if needed half-closed needle latches can be re-opened. In preventing the premature closure of the needle latches, a mechanical contact takes place between the latches and the yarn feeder, and on account of the relative movement between the needles and the yarn feeder, some needle wear is unavoidable. To keep this wear to a minimum, proper adjustment of a yarn feeder of this kind is critical; and it can be performed only by highly skilled operators.
Aside from this, threading the yarn into the small yarn guide bore of the yarn feeder is time-consuming and difficult, depending on the yarn material (crimping of the yarn caused by untwisting, or bunching, may occur), and can usually be accomplished only with the aid of auxiliary tools. Knots in the yarn, produced for instance by a yarn knotter, not infrequently become snagged in the yarn guide bore and come untied or break, especially if the yarn is deflected severely by the yarn feeder. A stitch, and hence a drop-off of the knit goods, and stoppage of the machine are the immediate consequences. Particularly in knitting with cotton yarns, there is the additional problem that the yarn feeder accumulates fluff, which leads to a constriction of the yarn guide bore, thereby hindering the yarn path. The end result, again, is yarn breakage and a drop-off of the knit goods.